The present invention relates to a multilayer optical recording medium including an N (N≦5) number of interfaces capable of reflecting incident light.
For example, optical recording media such as a CD (Compact Disc), a DVD (Digital Versatile Disc), and a BD (Blu-ray Disc: registered trademark) are widely used.
In a recordable optical recording medium including a recording film among such optical recording media, many recording films are provided in order to increase a recording capacity. In particular, in recent years, a multilayer optical recording medium including three or more recording films has been developed.
However, in the case of the multilayer optical recording medium, so-called interlayer stray light is generated and the occurrence of multiple interference becomes a problem. Here, the multiple interference means that, in the multilayer optical recording medium, two different light waves that are reflected on an interface capable of reflecting incident light one or more times interfere with each other, which causes a light intensity change on the detector. This occurs also through an interface including an unrecorded area.
Off course, it is desirable to prevent the occurrence of such multiple interference in order to prevent the reproduction performance from being lowered.    Patent Document 1: Japanese Patent Application Laid-open No. 2010-009685